Turner U.S. Pat. Nos. 2,757,573 and Chevalier 4,660,931 disclose viewers for stereoscopic pictures in the form of foldable viewers that may be mailed in flat, relatively compact packages and then opened for viewing. Cunningham U.S. Pat. No. 4,558,528 discloses a 3-D viewer having a series of scenes. Other patents in the field of this invention that may be of interest to invention historians include U.S. Pat. Nos. 2,986,830, 2,984,153, 906,774, 2,715,853 and 2,696,754. Foreign patents of interest include French 340,661 and European 275.